This invention generally relates to tamper indicating plastic container closures, and more specifically to a threaded cap having a ring frangibly connected to a lower edge thereof.
Tamper indicating container closures are widely used to demonstrate to the final consumer that the contents of a container have not been contaminated or adulterated subsequent to the time the closure was initially secured onto the container. One type of tamper indicating container closure comprises a threaded cap and a ring frangibly connected thereto. The ring, which may or may not be split, is located generally concentric with and slightly outside a lower portion of the cap, and the ring is connected thereto by means of a plurality of frangible members. The ring includes a multitude of inside pawl members, and the closure is intended for use with a container having a plurality of outside teeth that engage the inside pawls of the ring as the closure is twisted off the container. This engagement tends to break the frangible members connecting the ring to the cap, separating the ring therefrom. Closures of this type are described in greater detail in U.S. Pat. Nos. 4,062,466; 3,874,540; 3,504,818; and 3,249,247.
One difficulty with prior art closures of this type is that the frangible members connecting the ring to the cap do not always break as the cap is twisted off a container, and hence that the cap may be removed from the container with the ring still connected to that cap. In particular, this may happen if one or more of the frangible members connecting the ring to the cap sufficiently stretches, without breaking, to allow the pawls of the ring to slide past the teeth of the container. The ring of such a closure may remain in a position similar to its original position relative to the cap of the closure; generally concentric with and slightly outside the lower portion of that cap. If the closure is again secured to the container, a casual observer may not notice the broken or stretched frangible members and may mistakenly assume that the closure has not been removed from the container after the closure was initially secured or mounted thereon.